From EP-B1-0 434 652, such a device is previously known in a telescopic boom arrangement, wherein a rotation motor at a rear end of a first boom portion is arranged to rotate a second boom portion. A rotation motor is positioned at the outer end of a second boom portion, which allows rotation of a feed beam for a rock drilling machine.
Through this arrangement, the rock drilling boom is maneuverable such that an operator can relatively easily position the feed beam in the desired position and direction with six degrees of freedom. The known device, however, makes it more difficult to make it possible to position with high precision, which is more and more essential for today's users. Because of the positioning and the arrangement of the first rotation motor, a certain rotational deviation that can not be neglected will be the result of play and deformation, which in practice makes it impossible to adjust with high precision.